1. Field of the Invention
The present invention relates to a reclamation unit for a liquid comprising a housing with a detachable upper and lower part where said lower part is connected with a base part which comprises at least one heating unit and a number of inlets and outlets where said upper part encloses at least one filter unit, and where the lower part and the base part form an evaporation chamber. The present invention furthermore relates to a filter unit, preferable for use in a reclamation unit.
2. Description of the Prior Art
In many types of equipment liquid is used as, for example a lubricant, a coolant, a propellant or the like, and the liquid is circulated in closed systems. Even so the liquid is exposed to, for example temperature changes, contaminants, and water that degrades the efficiency of the liquids as, for example a lubricant, a coolant or a propellant, and there is a risk of damaging the equipment by circulating the liquid too many times in the closed system.
One very expensive and impractical way to resolve this problem is to supply a continuous flow of new liquid to the equipment and discharge the liquid when it has passed through the equipment.
A more practical solution is to fit the equipment with a reclamation unit that provides removal of solid contaminants and water when liquid is passed through the reclamation unit. The reclamation unit can either process all the liquid or be a by-pass unit that continuously processes a fraction of the fluid so that the liquid is maintained at a high level of quality.
EP-A2-0 295 871 describes an oil reclamation device where oil is lead through a filter unit and an evaporation chamber for removal of water and solid contaminants, and where the evaporation chamber is positioned above the filter unit.
WO-A1-97/26978 describes an oil reclamation device where oil is lead through a composite filter unit and an evaporation chamber for removal of water and solid contaminants, and where the evaporation chamber is positioned above the composite filter unit.
WO-A1-96/23854 describes an oil reclamation device where oil is lead through a filter unit and an evaporation chamber for removal of water and solid contaminants, and where the evaporation chamber is positioned beneath the filter unit.
All three oil reclamation devices can remove water and solid contaminants when the oil is passed through the devices, but there are a number of disadvantages in the construction of these devices.
The devices all use a heating element encased in a base element of heat conductive material, which together with an approximately complementary part, forms the evaporation chamber. When the heating element is turned on, the heat will be distributed through the base element into, for example protruding fins or ring walls of the counterpart upon which a thin oil film will pass, hence the oil is heated and the water is evaporated.
A main disadvantage of this construction of the evaporation chamber where there is a direct contact between the heat surface and the oil, is that there is a high risk of superheating the oil whereby the characteristics of the oil will be changed and thus the oil becomes unusable with the connected equipment.
Another disadvantage of this construction of the evaporation chamber is that the walls of the entire evaporation chamber are heated, and the desired temperature in the evaporation chamber or on the contact surfaces will only be obtained with a high energy consumption because there is a relatively high energy loss to the enclosing environment and the material mass of the base element, and the protruding fins or ring walls must be heated.
Yet another disadvantage of this construction of the evaporation chamber is that when the oil is heated, it causes heat loss from the oil, and furthermore the heating of the oil will not contribute to further evaporation of water.
Both EP-A2-0 295 871 and WO-A1-97/26978 describe oil reclamation devices where the evaporation chamber is positioned above the composite filter unit which is a disadvantageous construction where any change of the composite filter unit could lead to spillage of oil.
In EP-A2-0 295 871 the filter material is compressed cotton and polypropylene fibers with an oxidation inhibitor.
In WO-A1-97/26978 the filter material is twisted continuous filament of unbleached natural cotton in the by-pass filter and filter where the filament is compressed differently in order to control the cleaning efficiency of the filters.
In WO-A1-96/23854 a filter material like, for example unbleached natural cotton fibers is used which can filter solid contaminants from the oil. The compression of the fibers varies throughout the filter material, thereby controlling the cleaning efficiency of the filter.
The disadvantage of using a filter material with intentional varying compression throughout the filter material is that the production of the filter unit becomes complicated because it is necessary to precisely control the compression of the filter material in order to obtain the necessary cleaning efficiency of the filter without the risk for clogging.
The disadvantage of producing a filter unit with a filter and a by-pass filter is that it is a more complicated construction, hence a higher cost for the filter unit.